Krenn comes from Göstling an der Ybbs in Lower Austria . He was two-time Austrian student champion in giant slalom , won the giant slalom at the Trofeo Topolino in 2007 and was three-time Lower Austrian regional champion in both 2007 and 2008. From December 2009 he started to compete in FIS races . In February 2011 he was a participant in the European Youth Olympic Festival in Liberec . Due to a torn cruciate ligament , he missed the entire 2011/12 season. Then he gradually specialized in the fast disciplines. The first appearances in the European Cup followed in mid-January 2015 .
At the end of December 2015, Krenn won an FIS race for the first time. He celebrated his first European Cup victory on December 21, 2016 at the Super-G on the Reiteralm . Six days later he made his World Cup debut: In the Super-G of Santa Caterina , he finished 28th and immediately won World Cup points. However, he injured his knee slightly, which forced him to take a break of several weeks. Recovered again, he won the Austrian junior downhill championship title in mid-February 2016. In the winter of 2016/17 he mostly competed in the European Cup, while there were no World Cup appearances. At the end of December 2017, he again won the European Cup Super G on the Reiteralm. In addition, there were two further podium places during the 2017/18 season. With that he decided the Super-G discipline ranking for himself and thus secured himself a permanent World Cup starting place.
On December 1, 2018, Krenn surprisingly finished sixth in the Super-G at Beaver Creek with a high starting number.